Alpha CAM filter particle collection pattern study results

摘要

During a January 1991 Westinghouse Internal Audit of the WIPP Radiological Air Monitoring Program, an auditor observed that on an Eberline Alpha-6A CAM filter, some particulate was deposited outside the 25 mm diameter area that the filter is planned to use. Since the CAM uses a 25 mm diameter detector, this observation raised concern that the operational efficiency may be affected by the spread of filtrate. A (Eberline Alpha-6A) CAM particle collection pattern study was undertaken to determine if any significant sensitivity loss resulted from the broadened filtrate area and then to determine actions to improve performance if required. The results of this study provide documentation of the filtrate patterns on each of the Eberline Alpha-6A CAMs in use at the WIPP. In addition, data is reported that shows the results of some changes to the CAM sampling system that appear to improve the edge definition of the collected material on the filter. An important conclusion is that the relatively small spread of filtrate is consistent from CAM to CAM and studies by Texas A&M show that the majority of respirable size particles are collected in the center of the 25 mm diameter pattern while the visible particles that were deposited outside the pattern were of non-respirable size. Both this study and previous documented studies indicate that the Eberline Alpha-6A CAM provides efficient sampling and measurement of airborne alpha emitting particles and that it helps meet WIPP commitment to ''ALARA'' in its radiation safety program. No charges in the Eberline Alpha-6A sampling system were found necessary as a result of this study.